U.S. patent application number 10/739504 was filed with the patent office on 2005-06-23 for removable cartridge recording device incorporating antiferromagnetically coupled rigid magnetic media.
Invention is credited to Griffith, David W., Thomas, Fred C. III.
Application Number | 20050135009 10/739504 |
Document ID | / |
Family ID | 34677623 |
Filed Date | 2005-06-23 |
United States Patent
Application |
20050135009 |
Kind Code |
A1 |
Thomas, Fred C. III ; et
al. |
June 23, 2005 |
Removable cartridge recording device incorporating
antiferromagnetically coupled rigid magnetic media
Abstract
A removable magnetic data storage cartridges incorporates
antiferromagnetically coupled (AFC) media and may be used with a
data drive to push the capacity point of removable hard platter
based magnetic storage to 35 GB for a single platter 2.5" form
factor product. The removable magnetic data storage cartridges
incorporating AFC media represents an equivalent increase in the
areal density of removable magnetic data storage cartridges on the
order of 13.times..
Inventors: |
Thomas, Fred C. III; (Ogden,
UT) ; Griffith, David W.; (Layton, UT) |
Correspondence
Address: |
James T. Hagler
Iomega Corporation
10955 Vista Sorrento Parkway
San Diego
CA
92130
US
|
Family ID: |
34677623 |
Appl. No.: |
10/739504 |
Filed: |
December 18, 2003 |
Current U.S.
Class: |
360/133 ;
G9B/23.033; G9B/23.036; G9B/23.039; G9B/33.042 |
Current CPC
Class: |
G11B 23/0308 20130101;
G11B 23/0312 20130101; G11B 23/0316 20130101; G11B 33/1446
20130101 |
Class at
Publication: |
360/133 |
International
Class: |
G11B 023/03 |
Claims
What is claimed is:
1. An information storage cartridge comprising: a magnetic disk
type information storage medium having at least one information
storage surface thereon, wherein the information storage surface
has an antiferromagnetically coupled data recording layer; and a
physical access port to said information storage medium for
external insertion of at least one head, wherein the head reading
information from and writing information to the information storage
surface.
2. The information storage cartridge of claim 1, further comprising
a glass substrate for the information storage medium.
3. The information storage cartridge of claim 1, further comprising
a metal substrate for said information storage medium.
4. The information storage cartridge of claim 1, further comprising
a flexible plastic substrate for said information storage
medium.
5. The information storage cartridge of claim 1, further comprising
a GMR read element incorporated in said head.
6. The information storage cartridge of claim 1, further comprising
a data error correction component implementing dual layer data
block correction.
7. The information storage cartridge apparatus of claim 1, further
comprising a motor for rotating the information storage medium in
the cartridge.
8. The information storage cartridge of claim 1, further comprising
an electrical connector on the information storage cartridge.
9. The information storage cartridge of claim 1, further comprising
an environmental control element.
10. The information storage cartridge of claim 9, wherein the
environmental control element includes an absorbent filter.
11. The information storage cartridge of claim 9, wherein the
environmental control element includes a nuclear emitter.
12. The information storage cartridge of claim 1, further
comprising a retractable shutter for said physical access port.
13. The information storage cartridge of claim 1, wherein data
tracks on said information storage medium have a width of 0.75
microns or less.
Description
TECHNICAL FIELD
[0001] This invention relates to removable physical storage, and
more particularly to removable cartridge incorporating
antiferromagnetically coupled rigid magnetic media.
BACKGROUND
[0002] The demand for removable magnetic cartridge data storage
devices with larger and larger capacities and higher transfer rates
continues to grow with the capacity of other forms of data storage
such as the hard disk drive (HDD). Industrywide, HDD capacity has
grown an average of 60 percent per year since 1991. Software
applications, particularly those using audio and video, continue to
drive the increasing demand for greater storage capacity. Video is
the major capacity driver for the HDD industry today.
[0003] In the future, the Internet is expected to play an
increasing role in the growth of multimedia applications that
require large HDD capacities. Today, most Web sites employ text and
static graphics to exhibit their content. But, as the use of
broadband communication technologies such as integrated services
digital network (ISDN), asymmetric digital subscriber line (ADSL),
and cable modems increases, the use of bandwidth-intensive
audio/video technologies on the Internet will also increase. This
greater Internet access will, in turn, stimulate the development of
new graphics applications and programs that will generate
additional demand for HDD capacity.
[0004] Examples of the kinds of applications that are expected to
grow in popularity and further push the requirements of removable
cartridge data capacity envelope are:
[0005] E-commerce--The online shopping experience will include
greater use of audio and video (including 3D video) content. For
example, new car shoppers will be able to view full-motion
audio/video (AV) files that will provide a fairly accurate idea of
an automobile's performance characteristics under different driving
conditions. The AV file will be downloadable for later viewing and
comparison with other automobile files. Similarly, future mall
shoppers will be able to browse virtual shopping centers and
digitally "handle" the virtual merchandise by picking 3D objects
and manipulating them on their computer screens. For example,
furniture shoppers might furnish virtual rooms in their homes by
viewing them in 3D perspective.
[0006] Photo/Video/Audio Libraries--With the advent of digital
cameras and camcorders with digital audio capabilities, PC users
can use their HDDs as virtual libraries of photos and videos. The
resulting storage requirement will be extensive. With compression,
1,000 reasonably high-resolution images can be stored in 1 GB of
disk space. Good-quality compressed video such as Video Home System
(VHS) or Moving Picture Experts Group level 1 (MPEG-1) requires
about 1.5 Mbps, or about 5.5 gigabits per hour (Gb/hr).
High-Definition Television (HDTV) or the equivalent MPEG-2 will
increase required storage to approximately 10 Gb/hr.
[0007] AV e-mail--Unlike today's primarily text-only e-mail, most
e-mail messages will be able to support full-motion video and audio
content. Many of these large-capacity messages will be downloaded
to the HDD for later action. Depending on file length and file
compression level, AV e-mail files will typically range in size
from 2 MB to 15 MB or greater.
[0008] Education--As more universities and other professional
educational institutions offer online programs, multimedia
applications will become widespread. Media clips will be included
in material sent to students to be downloaded for individual study,
and medical doctors will receive surgical updates on new procedures
in full-color video and audio.
[0009] Corporate Communications and Training--Currently, these
applications are primarily intranet in nature, and include such
activities as employee communications, executive updates, training
modules, and so forth. Content is generally text and static graphic
images. However, as streaming media technology improves, AV modules
will be sent over the company network and downloaded to the user's
HDD for later study at the user's convenience.
[0010] The magnetic recording layer on removable magnetic data
storage drives has been what is termed "sputtered thin film
magnetic media". This has been the principal rigid platter media
type for approximately the past 25 years. Prior to its invention
oxide and plated media were the state of the art for rigid disk
based magnetic recording devices.
[0011] Prior art sputtered thin film magnetic media is typically
coated with multiple layers. Most disks are aluminum or glass,
plated with a nickel-phosphorous layer, followed by chrome or
chrome alloy. The chrome layer is followed by the magnetic layer,
usually a cobalt alloy, which is capped by a topcoat, a layer to
provide protection against corrosion and wear from the head. A
lubricant is finally applied to the disk to further reduce friction
between the head and disk.
[0012] Companies such as Iomega Corporation have previously built
and brought to market removable cartridge recording devices
incorporating rigid magnetic media incorporating sputtered thin
film magnetic recording layers. The Iomega Jaz 1 GB and Jaz 2 GB
are two examples of such products. To accommodate the demand for
greater storage capacity, a removable magnetic data storage
cartridge having much greater storage and areal densities is
needed.
SUMMARY
[0013] A removable magnetic data storage cartridges incorporates
antiferromagnetically coupled (AFC) media and may be used with a
data drive to push the capacity point of removable hard platter
based magnetic storage to 35 GB for a single platter 2.5" form
factor product. The removable magnetic data storage cartridges
incorporating AFC media represents an equivalent increase in the
areal density of removable magnetic data storage cartridges on the
order of 13.times..
DESCRIPTION OF DRAWINGS
[0014] These and other features and advantages of the invention
will become more apparent upon reading the following detailed
description and upon reference to the accompanying drawings.
[0015] FIG. 1 illustrates a removable magnetic data storage
cartridge incorporating AFC technology.
[0016] FIG. 2 illustrates removable media system incorporating the
removable magnetic data storage cartridge of FIG. 1.
[0017] FIG. 3 compares projections made based on measurements of
the expected signal amplitude loss after 10 years in conventional
single-layer media with that in AFC media.
DETAILED DESCRIPTION
[0018] FIG. 1 illustrates one embodiment of the invention. This new
ultra-high capacity removable cartridge 100 magnetic disk drive
incorporates the use of an antiferromagnetically coupled (AFC)
media recording layer 140. The removable cartridge 100 includes a
cartridge top 105 and a cartridge bottom 110. The cartridge top 100
includes a physical access port 125 for read/write heads to access
the AFC recording layer 140. An access port shutter 115 covers the
physical access port 125 when not in use. An elastomeric seal 120
is positioned between the access port shutter 115 and the access
port to prevent impurities from entering the cartridge 100. Use of
elastomeric seals 120 on the cartridge 100 and on the drive unit
isolates contamination sensitive elements in unit (media and heads)
from contaminated ambient air. An example can be found in the
co-pending application entitled "Enhanced Airflow Conditioning
System for Removable Data Storage Cartridge," filed Nov. 15, 2002,
which is incorporated by reference herein.
[0019] The cartridge 100 includes an electrical connector 130. The
use of an electrical connector 130 on the data storage cartridge
100 may be used for linkage to a solid state device in cartridge
100. An example can be found in the co-pending application entitled
"Method and Apparatus for Electrically Coupling Components in a
Removable Cartridge" Ser. No. 09/590,508, filed Jun. 9, 2000, which
is incorporated by reference herein.
[0020] The cartridge 100 also includes a motor base plate 145 which
houses a media rotational motor 150. Location of the media
rotational motor 150 in the removable cartridge 100 rather than in
drive reduces media radial and vertical run-out and hence makes the
difficult servo task of data track following after cartridge
interchange between drive devices easier. An example can be found
in the co-pending application entitled "Removable Cartridge with
Sealed Motor Hub and Motor Bearing in Cartridge" filed Nov. 15,
2002, which is incorporated by reference herein.
[0021] Additionally, the cartridge 100 may contain cartridge
environmental control elements 135 which assist in removing
impurities from the cartridges. Examples of environmental control
elements 135 include absorbent filters to control the relative
humidity and eliminate corrosive gases. The absorbent filters may
be made with materials such as activated carbon, impregnated
activated carbon, or silica gel. The environmental control elements
135 may be integrated into the removable cartridge 100 in the form
of absorbent breather filter, absorbent recirculation filter,
and/or absorbent pouches. The environmental control elements 135
may also include nuclear material emitting Alpha or Beta particles
places proximate to electrostatic discharge (ESD) sensitive
components or electrical paths leading to such ESD sensitive
components. The nuclear particles ionize the surrounding air
molecules. The ionized air molecules recombine with the ions of a
static charge neutralizing the charge and thus eliminating or
reducing the potential of ESD damage to the components.
[0022] FIG. 2 illustrates a drive 200 which receives the removable
cartridge 100 of FIG. 1. The drive 200 includes seal mating means
205 which combine with the seal 120 to create an airtight
connection between the drive 200 and the cartridge 100. The drive
200 also includes a head actuator assembly 215 which transports
read/write heads 210 through the physical access port 125 to
interact with the AFC recording layer 140. The read/write heads 210
may incorporate gigantic magneto-resistive (GMR) magnetic head read
elements. Further, the read/write heads 210 may ride on a
head/suspension load and unload ramp in the removable data storage
cartridge (not shown). Inclusion of a portion to the
head/suspension load and unload ramp in the removable data storage
cartridge 100 makes the mechanical task of ramp alignment with
interchange of data storage cartridges 100 much easier and
accurate. An example can be found in the co-pending application
entitled "Bifurcated Load Ramps for Removable Cartridge", filed
Nov. 15, 2002, which is incorporated by reference herein.
[0023] The AFC recording layer 140 may incorporate the use of a
glass substrate for the media. Glass substrates provide about a
3.times. improvement over aluminum media to shock as well as
head/media slap robustness. However, the AFC recording layer 140
may also be used with a plastic or flexible substrate. The AFC
recording layer 140 may also use multilayer interactions and
permits longitudinal recording to achieve a future data density of
100 gigabits/inch.sup.2--four times the data density of previous
products--without suffering from the projected data loss due to
thermal instabilities. Antiferromagnetically coupled (AFC) media
delays for several years the impact of superparamagnetism in
limiting future areal density increases.
[0024] The superparamagnetic effect originates from the shrinking
volume of magnetic grains that compose the hard-disk media, in
which data bits are stored as alternating magnetic orientations. To
increase data-storage densities while maintaining acceptable
performance, designers have shrunk the media's grain diameters and
decreased the thickness of the media. The resulting smaller grain
volume makes them increasingly susceptible to thermal fluctuations,
which decreases the signal sensed by the drive's read/write head.
If the signal reduction is great enough, data could be lost in time
to this superparamagnetic effect.
[0025] Historically, disk drive designers have had only two ways to
maintain thermal stability as the media's grain volume decreases
with increasing areal density: 1) Improve the signal processing and
error-correction codes (ECC) so fewer grains are needed per data
bit, and 2) develop new magnetic materials that resist more
strongly any change to their magnetization, known technically as
higher coercivity. But higher coercivity alloys also are more
difficult to write on. While improvements in coding and ECC are
ongoing, AFC media is a major advancement because it allows
disk-drive designers to write at very high areal densities but is
much more stable than conventional media.
[0026] Conventional disk media stores data in only one magnetic
layer, typically of a complex magnetic alloy (such as
cobalt-platinum-chromium-b- oron, CoPtCrB). AFC media is a
multi-layer structure in which two magnetic layers are separated by
an extraordinarily thin--just three atoms thick--layer of the
nonmagnetic metal, ruthenium. This precise thickness of the
ruthenium causes the magnetization in each of the magnetic layers
to be coupled in opposite directions--anti-parallel--which
constitutes antiferromagnetic coupling.
[0027] When reading data as it flies over the rapidly rotating
disk, a disk drive's recording head senses the magnetic transitions
in the magnetic media that coats the disk. The amplitude of this
signal is proportional to the media's "magnetic thickness"--product
of the media's remanent magnetic moment density ("Mr") and its
physical thickness ("t"). As data densities increase, the media's
magnetic thickness (known technically as Mrt) must be decreased
proportionately so the closely packed transitions will be sharp
enough to be read clearly. For conventional media, this means a
decrease in the physical thickness of the media.
[0028] The key to AFC media is the anti-parallel alignment of the
two magnetic layers across each magnetic transition between two
bits. As it flies over a transition, the recording head senses an
effective Mrt of the composite structure (Mrt.sub.eff) that is the
difference in Mrt values for each of the two magnetic layers:
Mrt.sub.eff=Mrt.sub.top-Mrt.sub.bottom
[0029] This property of the AFC media permits its overall Mrt to be
reduced--and its data density increased--independently of its
overall physical thickness. Thus for a given areal density, the Mrt
of the top magnetic layer of AFC media can be relatively large
compared with single-layer media, permitting inherently more
thermally stable larger grain volumes.
[0030] FIG. 3 compares projections made based on measurements of
the expected signal amplitude loss after 10 years in conventional
single-layer media with that in AFC media. As the Mrt of the
conventional media decreases with reduced film thickness and grain
diameter, thermal effects rapidly shrink its magnetic amplitude.
This dramatic signal loss is at the heart of the superparamagnetic
effect. Acceptable levels of signal decay vary depending on system
design but typically range between 10-20%. In comparison, AFC media
has the thermal stability of conventional media having about twice
its magnetic thickness. In the future, AFC media structures are
expected to enable thermally stable data storage at densities of
100 gigabits per square inch and possibly beyond.
[0031] Two additional advantages of AFC media are that it can be
made using existing production equipment at little or no additional
cost, and that its writing and readback characteristics are similar
to conventional longitudinal media. The output pulse sensed by the
recording head is a superposition of the fields from transitions in
both the top and bottom magnetic layers. As with conventional
media, this output is detected as a single pulse, so no changes to
the disk drive's recording head or electronic data channel
components are required.
[0032] AFC magnetic media was developed for use in hermetically
sealed fixed hard drives. The distance between the read/write head
fly over this media is on the order of a micro-inch or {fraction
(1/40)}.sup.th of a micron. The width of data tracks is on the
order of 0.75 microns or less. These tiny dimensions and
maintaining the ability to both tribologically continuously fly the
head at this height and track-follow to these dimension in a
removable storage product is perceived to be untractable tasks by
others and hence to this point in time no-one else has incorporated
this technology in anything other than a hermetically seal fixed
hard drive.
[0033] Embodiments of the present invention include features in a
removable storage cartridge to achieve these specifications,
including the use of 2-layer error correction code, this is
alternately called "product code," matrix ECC, or DVD like ECC. An
example of an error correction code can be found in the co-pending
application entitled "Pacing of Data Though Random Access Disk
Drive that Incorporates a Two Dimensional Error Code" U.S.
application Ser. No. 10/447,923, filed Mar. 29, 2003, which is
incorporated by reference herein.
[0034] Numerous variations and modifications of the invention will
become readily apparent to those skilled in the art. Accordingly,
the invention may be embodied in other specific forms without
departing from its spirit or essential characteristics.
* * * * *